Catalytic Converter 1991 YJ 4.0

[baldjohnny]

Have a small crack in the exhaust manifold and thought about putting some headers and a catback system on to "fix" it. Climbed under the Jeep to scope it out and noticed that the old owner had removed the Cat. Looks like they cut it out and welded a straight pipe in. A little consternation resulted since they've just approved the start of emissions testing in our county, but figured it can't be that bad. A little extra money but doable.

One thing that does have me puzzled is the manual (Chilton) that refers to a "downstream air injection tube" which attaches to the converter. Looking at some models of converters online of ones that fit my Jeep's year show this connection.

Where does it hook up to on the engine? Special material or tubing, don't know, sure whatever it has has to be able to take a little heat. Anyone have any help/ suggestions on this, because the Chilton isn't guiding me very well on this...

Thanks!

 

[Bounty__Hunter]

The tube on the cat should be capped on '91+ YJ's.

 

[yo momma yj]

mid 90s had a cat recall with replacement...(the replacement rusts out too)
check to see if yours was covered under the recall. if the Gods are smiling, you could win a free-bee


>Where does it hook up to on the engine?

my guess is an intake pre heat?
if so, then it's for high temp complete burn for clean emissions.

 

[baldjohnny]

Thank you. I haven't seen any extra lines that look like they've been capped, or should be attached to something, so that had me wondering.